Concrete

Removing Epoxy and Coatings: PCDs vs Scarifiers

Choosing between PCD grinding, scarifying and shot blasting to remove epoxy and other coatings, based on thickness and what goes down next.

Updated · 2 min read

Coating removal is about thickness: thin coatings grind off, while thick epoxy and elastomerics need PCDs or a scarifier. Shot blasting works on thin, brittle coatings but struggles with thick or rubbery ones.

Silica and old coatings

Grinding, scarifying and blasting all create silica dust; follow OSHA Table 1.[5] Some old coatings and adhesives may contain lead or asbestos. Test before you remove anything you can't identify; see Cutback adhesive and asbestos ID and OSHA 1926.1101.[6]

Compare the methods

What each machine is suited for:[1][2][4]

Method Best for Limits
Grinder with metal bond Thin coatings; 16-grit segments take off thin epoxy, paint, adhesive and sealers[1] Loads up on gummy coatings
Grinder with PCD Thick epoxy, membranes, mastic Leaves a rough surface; follow with metal bond
Scarifier Thicker epoxy and elastomeric coatings Leaves grooves; some coating systems require shot blasting afterward[4]
Shot blaster Thin, brittle coatings The A95 isn't recommended for urethane over 10 mil, and well-bonded epoxy can't come off without deep blast damage to the concrete[2]

PCD choices

PCDs come in two styles.[3] Without sacrificial bars they're very aggressive and leave a coarse profile on the concrete underneath; with sacrificial bars they cut more gently and don't damage the concrete. Run either style at low RPM.[3] Follow PCD with metal bond, since PCDs usually profile the concrete under the coating.[1]

Profiles you'll end with

Scarifying typically leaves CSP 6 to 9, and grinding CSP 1 to 3.[4] Aluminum oxide pads only polish, so they aren't a removal tool.[4] If the next product needs a lighter profile than the removal method leaves, plan a second step. See ICRI CSP profiles.

Step by step

This sequence covers most coating removals.

  1. Identify the coating and its thickness, and test anything old or unknown.
  2. Set up dust collection matched to the machine. See Dust extraction.
  3. Take off the bulk with PCD or a scarifier.
  4. Clean up and even out with metal bond (or shot blast after scarifying), then edge with a shrouded hand grinder.
  5. Check the profile against what the next product needs.

Common mistakes

These burn time and tooling.

  • Metal bond on thick epoxy. The segments glaze and stop cutting.
  • Leaving a scarified surface as-is. Some coating systems require shot blasting afterward.[4]
  • Aggressive PCD where the slab needs to stay smooth. PCDs without sacrificial bars leave a coarse profile.
  • Shot blasting thick urethane. The A95 isn't recommended over 10 mil.[2]

Equipment we carry

These are the removal tools and machines we stock.

References

  1. National Flooring Equipment: Grinder tooling guide
  2. National Flooring Equipment: A95 shot blaster performance guide
  3. Superabrasive (Lavina): PCD tools
  4. Sika: Surface preparation guide
  5. OSHA 1926.1153, Table 1
  6. OSHA 1926.1101, Asbestos (construction)

Linked PDF documents are archived copies saved by PreFloor Tools so they stay available if the publisher moves or removes them. Check the publisher's website for the latest revision.

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